Automobile heater



July 21, 1953 FR 2,646,258

AUTOMOBILE HEATER Filed Oct. 27, 1949 2 Sheet s-Sheet 1 INVENTOR. l/ Mnee/1' P. M. FREER AUTOMOBILE HEATER Jl lly 21, 1953 2 Sheets-Sheet 2Filed Oct. 27, 1949 i7 INVENTOR.

7%22): vAZ' 7766/? yfi irra/m f Patented July 21, 1953 UNITED STATESPATENT OFFICE V Phelps M. Freer, Detroit, Mich. Application October 27,1949, Serial No. 123,841-

6 Claims. (Cl. 257137) This invention relates to heat exchange devicesand, in particular, to heaters cf the type that may be used inautomobiles and the like.

It is an object of the invention to increase the heat transferefficiency of heaters of the type described and thus reduce thesize-capacity ratio and the cost of the heater unit.

Another object is to provide a heater that may be economically made fromsheet metal parts.

These and other objects of the invention are accomplished by means of aheater construction in which the conduit or coil for the fluid heatingmedium is of sinuous shape and preferably made from originally flat,spaced, superposed sheets of metal secured together at theirside edges.The sinuous coil is placed in a sheet metal box that has bulges in thesides upon which the curved portions of the coil rest whereby the coilis fitted into and supported by the sides of the box. A

cover is yieldably attached to the box to-close the opening throughwhich the coil is inserted and serves as a side thereof. Each of thesides of the box which is normal to the sides that support the coil isformed with bulges that are staggered with respect to the bulges in theopposite side and serve to direct air back and forth in sinuous passagefrom one loop to another of the coil. The coil is formed withprojections and fins that serve to create turbulent air low and this maybe further promoted by the use of irregularly surfaced divider platesbetween adjacent sections of the coil. The core formed by the box andcoil may be encased at opposite walls by inlet and outlet manifolds and,if desired, a flow impeller may be secured to one of the manifolds toform a selfcontained heater unit. l

By virtue of the foregoing construction, the heater is endowed with anextremely large area of heat-conducting contact between air and coil.The use of fins on the coil serves also to transfer heat to the air byradiation. The turbulence provoking projections" and the fins tend tocause air flow thatremoves the boundary layer andrthe divider platetends to prevent stratification, thus providing optimum conditions forthe transfer of 1 heat from the heating liquid to the air. Theturbulence' projections also increase the surface area of the coil andserve to create some turbulence in the heating liquid flowing therein.The net result of these and 'otherfeatures is to provide a 1 high rateof heat transfer in a small-size unitr Other objects and features of theinvention will become apparent upon consideration of the ac-.

2 Fig. '4 is a section taken on line 4 4 of Fig. 2; Fig. 5 is anenlarged view of the structure contained with the circle 5 of Fig. 2;and Fig. 6 is a sectional view of a plug valve that may be usedinforming the'sinuous coil'of the invention.

The automobile heater of this invention has a sinuous thin-walled'heatexchange coil l for the passage of heating liquid from the radiator. Itcomprises a plurality of straight sections 3 (Fig. 4), each of which isjoined at its ends to an adjacent straight section by a recurved section5. The internal sinuous passage for fluid is designated by the referencenumeral i. This coil is designedto give a high ratio of surface area tovolume and therefore itswidth and its loop length (distance betweenoppositely disposed recurvatures 5) are substantially larger than itsthickness. While the coil surfaces are illustrated as flat, they may beundulated or corrugated to increase the surface area and desirablyaffect fiuid flow. The coil is made of suitable corrosionresistantmaterial, copper being the conventional material for this purpose. Thecoil may be formed from different types of raw stock, and it is notintended to limit the invention, in its broad aspects, to the history ofmanufacture of the coil. For example, the coil may be bent from tubingthat is originally formed to the desired cross sectional shape. Again,it may be formed by flattening round tubing and then bending the productinto sinuous shape Advantage is more read- I ily taken of certain detailfeatures of the invention, however, .when'the' coil is formed fromoriginally fiat sheet metal. It is possible to make the coil tubeflfr'omsheet metal in either of two ways, the-second of which is preferred andillustrated'herein, via. (1) by forming and folding a single sheet ofmetal and then securing its edges as bestindicated in Fig. 5. It will berecognized that generically the coil formed by either of these 'twomethods may be described as one comprised of a pair of spaced superposedsheets having their side edges sealinglyinterconnected or securedtogether) The opposite faces or pieces I I of the coil each "have 'amultiplicity of outwardly extending. projections or bosses l3 pressedtherein which are generally round in cross section. They serve to createturbulence in the air flowing by and thus to. cause some scrubbing ofthe boundary layer, and also increase the surface areaand causeturbulence in the heating fluid flowing through the coil. The coilpieces I I also have generally round inward projections iii that serveto maintain the y proper spacing between the pieces and which may thusengage similar projections on opposite coil pieces, as illustrated, orbe of a length equal to the width of the passage so as to engage theflat face of the opposite piece. The projections I are sufficiently fewin number so that they do not appreciably interfere with the flow ofwater through the passage 7, though it is desirable that they createsome turbulence in liquid flowing through the coil. The upper open endof the coil I (Fig. 4) forms the outlet for water and is adapted todischarge it into a suitable hose by a length of pipe or tubing II thathas a slot I9 therein registering with the end opening of the coil. Theends of the pieces II may be flanged at ZI and soldered to the surfaceof the tubin I'i, a indicated, to effectuate the desired watertightconnection. The lower open end of the coil Iforms the inlet for waterfrom the radiator and is provided in a similar manner with a pipe ortube 23.

The coil I may be manufactured by several methods, features of whichobviously may be used in constructing the coil from various of the typesof raw stock mentioned above. In one method straight dished pieces IIwith the projections formed therein of the developed length of the coilare separately bent into sinuous form, placed together, and the edgesclamped and soldered. In another method, straight pieces of thedeveloped length are joined together by soldering of the flanges 9 afterthe projections I3 and I5 have been formed therein but prior to bendinginto sinuous shape. The outlet and inlet tubes ii and 23 are preferablyattached to the ends before bending. The sections of the pieces 5 Iwhich are to form the outside of the curved sections 5 are desirablyprovided before soldering with outward- 1y pressed arcuate ribs 25 (Fig.4) that extend the full width of the coil. The diameters or chords ofthese ribs expand during bending of the pieces into the curved section 5to prevent flattening at those sections. As a further precaution againstflattening and undesired restriction of passage I, the straight flattube is preferably filled with water (or other substantiallyincompressible liquid) prior to bending into the sinuous form. This maybe done by plugging both of the pipes I1 and 23. It is desirable that atleast one of these plugs be in the form of a pressure relief cap 21,such as shown in Fig. 6. The cap 21 comprises a plug body 29 that isadapted to sealingly fit in the end of a pipe, as pipe II. The body hasan aperture 3| which is enlarged to form a valve seat 33 and a springchamber 35. The body is threaded to receive an apertured retainer 31 tobear upon a spring 39 that holds the ball II on the seat 33 with adesired and adjustable force. It is obvious that if at any time duringthe bending of the flat soldered pieces II excessive diminuation ofvolume of the passage I takes place, the ball II will be forced off itsseat to relieve pressure in the passage and indicate that the bendingprocess is proceeding in an improper manner. Before this takes place,however, the liquid in the coil, being substan tially incompressible,will serve to prevent restriction of the passage I.

7 Instead of forming the coil I by bending continuous developed lengthsof the pieces II, a build-up procedure may be employed. In this methodflat sections of a length that accommodates less than all of the curvedsections 5 are bent and then joined with other sections to form thecomplete coil. For example, the coil may be built up from U-shapedsections that are provided at their ends with flanges, as indicated atA3 in Fig. 3. The flanges of enough sections are then soldered togetherto form the sinuous coil 2. In this method the spaced superposed sheetsmay be soldered together first and then bent, or Ibent first and thensoldered together.

The coil i fits in a sheet metal box 35 and these two elements form theheater core. The box has five integral sides and the sixth and open sideis closed by a cover :3? that has a flange that fits inside the box, asindicated at 49. The side walls 5| and 53 of the box that define theopen side of the box have bulges or curved sections 55 therein thatcorrespond to the curved sections 5 of the coil I. They, and also thetop and bottom 5'! and 59 of the box, also have cylindrical enlargementsIII to receive the pipes I? and 23 on the coil I. If the cover 41 isremoved from the box 45, the coil 5 can then be slipped into it, and thecurved sections 5 nt in and on the bulges 55 which therefore serve tosupport the coil. The curved sections 55 may have inwardly pressedprojections 63 therein to engage the coil I and facilitate thisassembly.

Air is allowed to flow in a sinuous path through the coil I by outwardlycurved sections 65 and 66 that are formed in the front wall 61 of thebox and in the cover i? thatforrns the rear wall of the box. The curvedsections '55 and 6B are adjacent the side flanges 9 of the coil andalternately place opposite sides of the straight coil sections 3 incommunication with each other.

Air enters the core through an inlet 69 that is formed in the cover 31and extends the width thereof and which registers with the air passagebetween the top two straight sections 3 of the coil. A similar openingII in the front wall 6'! adjacent the air passage between the bottom twostraight sections 3 of the coil forms the outlet for air. Between theinlet and outlet, the air flows downwardly back and forth between thestraight sections 3 of the coil I and between the curved front wallsections E35 and the curved rear cover sections $6. In the meantime,water or other heat-supplying medium flows upwardly from inlet pipe 23in the coil pass-age I back and forth be tween the sides 5! and 53 ofthe core to the outlet pipe II.

The cover 47 has suitable apertures for the passage of pipes I? and 23.It is yieldably held in place on the box 45 by several pins 12 thatextend through the box and may shoulder on the outside of the front wall6? and have a weak coil spring I3 thereon that is pressed against theoutside of the cover 4? by insertion of a cotter pin I4 through asuitable aperture in the pin. Inward movement of the cover i'I isprevented by the coil flanges 9. Alternate straight sections 3 that arestaggered in opposite sides of the coil have the flanges 9 squared offor cut off on a straight edge. These straight edges bear against flatsurfaces on the front wall 5? and cover 41 between the curved sections65 and Ed to determine the minimum overall front-to-rear dimension ofthe core which is ieldably maintained by the springs I3.

The front and rear of the core are enclosed by headers or manifolds 1-5and I7, respectively. These, like the box 55 and cover M, are preferablypressed from sheet steel and are adapted to receive the pipes II and 23.They shoulder on the box and cover as indicated at iii and aregenerically similar to covers and thus fit snugly on the box. The rearor inlet manifold 11 has a length of arched spring: wireiillsecuredibyapin or rivetj 83"to'the inside of its rear wall which bears uponthe-cover t? "and stresses the parts of the heater so as to preventrelative movement and rattling. Whenspring 83 is used, the pins '12 andcoilisprings 13 may be eliminated. The

manifolds are forced on their shouldered seats 19 .by bolts 85 thatextend through the entire assemblyof manifoldsand core. ir'I-he :rearmanifold is apertured at..8'i=to allowaircto flow to the inlet 69. Thefront manifoldhas anv opening 89 to allow air to flow fromthe outletfli.

:.An impeller may .beiused to "induce air flow through the presentheater and-may be placed on theinlet side to floweirthrough, but prefer-.abl is placed on the outlet side' thereof-to estab- .lish.a negativeair pressure which results-in more effective air flow, by the coil I.This maybeaccomplished by providingthe outlet manifoldit with a collarSisurrountiing the opening 89 and suspending therein a suitableflow-inducing fan 93. a

.It'is evident from .the structure already described that by providing acounter sinuous flow of-"air 'and-h'eatingwater in conjunction with a T"fiat surfaced sinuous coila maximum surface for heat conduction isachieved. The efficiency is increased further by providing the flanges 9i the coil I which fit'in the curved sectionsCb and 66 with fins,as'best illustrated in Fig'l'b. The

fins not'only furnishheat by radiation, but also fs'erve'to'increasejthe emcie'ncy of heat transfer I 1. heat exchanger comprisingspaced super- -posed sheets xsealingly secured together at theirside-ledges and of sinuous .form providing a sinu-' ous coil for heatingfluid, said sheets having out- .ward. turbulence-provoking bossesthereon, said Isheetshaving inward Jbossesthereon, portions of the sideedges :of said sheets being. inclined to theplane of the sheets to formradiation and turbulence-provoking; fins, an inlet pipe for the.coillcommunicatively secured to one end of the sheets, anoutletpipe-for the coil communica- :tiv.el-y secured to, the other endof the sheets a box having-outward bulgesina pair of opposite ;sidesthat-conform to, and receive and support -the.redurvitiesgot-the sinuouscoil, said box sides having inwardprojections therein engaging theSurfaceof the coil, said box having an opening in. aside normal to thesideswhich sup-port the sinuous coil wherebythe coil may be insertedinthe box, a cover for said opening, .meansyieldably {pressing the coveragainst the secured side edges of the "sheets" and forcing oppositesecured side edges ofithe sheets against the side of thebox oppositethe. cover, -said -,cov er,-; box, and coil definingya core, meansproviding inlet and outlet openings inthe walls of the core,- bulges inthe cover and the side opposite the cover for directingfiuid: to be'leatBdi-r-Q theinlet to the outlet by conduction 'bypromoting turbulentflow of] the air. Thefinsrareillustratedas being formed in twodifierentways. In one,th e double thickness of metal forming the soldered orbrazed flange 9 is extended-beyondthepreviously mentioned straight edgeflanges and then slit and bent alternatelyijn opposite directions toform the fins 95 that are radial with respect to the curved section-'6but spaced therefrom so as to attached alternately to the side walls 5!and 53- of the box by means offianges [0! at positions midway betweenstraight sections of the coil l. The plates have corrugations or ribsI63 transverse to the air flow pressed therein, which extend outopposite sides thereofto provide rigidity and by varying the size of theair passage create an aspirator effect that produces turbulence in theair flowing through the core. It is to be noted that'the plates 93provide these beneficial effects without materially reducing the size ofthe passage through which the air fiows. Obviously, the aspirator effectcan also be produced by making the coil surfaces of undulatory form.

The box ,5, cover 47, and manifolds and i1 may be employed as aself-contained heater and secured to the firewall of a vehicle bybrackets 1 H), as illustrated in Fig, 1.

Modifications may obviously" be made in. the

specific structure herein described. without departing from the spiritof the invention.

What is claimed is:

in -a sinuous path over the coil back and forth between the cover andthe side opposite, flow divider. plates having turbulence provoking ribsthereon located betweenadjacentsections of the coil, mamfold cover meansf tting the box over the inlet andoutlet openings for the fluid to beheated, spring means assooiate d with the mamfold cover meansapplyingyieldable pressure to the cover .for the box, said manifoldcover means having inlet and outletopenings incommunication with theinlet and outlet openings in the core, and impeller means for actuatingflow of fluid to be heated, saidimpeller means being located at"theioutlet of. the core to establish negative pr'essure inthe core, saidimpeller means .being supported'upon the manifold cover means.

2. An' auto heater comprising a tube having a width substantiallygreater than its thickness and of sinuous form providing a sinuous coilfor heatsupport the recurvities of the sinuous coil, said ing fluid, abox having outward bulges in a pair.

of opposite sides that conform to and receive and box having aremovable-side normal to the sides which support the sinuous coilwhereby the coil may be inserted in the box by movement transverse tothe length of the coil passes, means providing inlet and outlet openingsin the box, and bulges in the removable side and the side opposite theremovable side communicating with the spaces between the coil passes fordirecting fluid-to be heated from the inlet opening to the outletopening in a sinuous path over the coil back and forth between theremovable side and a a cover for said opening and forming a side of thebox, means providing inlet and outlet openings in'the box, bulges in thecover and the side opposite the cover communicating with the spacesbetween the coil passes for directing fluid to be heated from the inletopening to the Outlet opening in a sinuous path over the coil back andforth between the cover and the side opposite, and manifold cover meansfitting the box over the inlet and outlet openings for the fluid to beheated.

4. An auto heater comprising a tube having a width substantially greaterthan its thickness and of sinuous form providing a sinuous coil forheating fluid, a box having outward bulges in a pair of opposite sidesthat conformto and receive and support the recurvities of the sinuouscoil, said box having a removable side normal to the sides which supportthe sinuous coil whereby the coil may be inserted in the box by movementtransverse to the length of the coil passes, means providing inlet andoutlet openings in the box, and bulges in the removable side and theside opposite the removable side communicating with the spaces betweenthe coil passes for directing fluid to be heated from the inlet openingto the outlet opening in a sinuous path over the coil back and forthbetween the movable side and the side opposite, and impeller means foractuating flow of fluid to be heated.

5. An auto heater comprising a tube having a width substantially greaterthan its thickness and of sinuous form providing a sinuous coil forheating fluid, a box having outward bulges in a pair of opposite sidesthat conform to and'receive and support the recurvities of the sinuouscoil, said box having a movable side normal to the sides which supportthe sinuous coil whereby the coil may be inserted in the box by movementtransverse to the length of the coil passes, means providing inlet andoutlet openings in the box, bulges in the movable side and the sideopposite the movable side communicating with the spaces between the coilpasses for directing fluid to be heated from the inlet opening to theoutlet opening in a sinuous path over the coil back and forth betweenthe movable side and the side opposite,

and impeller means for actuating flow of fluid to be heated, saidimpeller means being located at the outlet of the core to establishnegative pressure in the core.

6. An auto heater comprising a tube having a width substantially greaterthan its thickness and of sinuous form providing a sinuous coil forheating fluid, a box having outward bulges in a pair of opposite sidesthat conform to and receive and support the recurvities of the sinuouscoil, said box having a movable side normal to the sides which supportthe sinuous coil whereby the coil may be inserted in the box, meansproviding inlet and outlet openings in the box, and bulges in theremovable side and the side oposite the removable side communicatingwith the spaces between the coil passes for directing fluid to be heatedfrom the inlet opening to the outlet opening in a sinuous path over thecoil back and forth between the removable side and the side opposite,and

resilient means for holding the removable side in place in the box.

- PHELPS M. FREE-R.

Number Name Date 154,368 Bon Aug. 25, 1874 203,842 Leland May 21, 1878953,252 Brinkman Mar. 29-, 1910 1,578,830 Jones et al Mar. 20, 19261,618,279 Fedders Feb. 22, 1927 1,788,447 Buck Jan. 13, 1931 1,992,835Newman Feb. 26, 1935 2,008,255 Larkin July 16, 1935 2,022,173 AlexanderNov. 26, 1935 2,028,456 Karmazin Jan. 21, 1936 2,107,031 Evans Feb. 1,1938 2,211,813 Franco-Ferreira Aug. 20, 1940 2,217,799 Giesler Oct. 15,1940 2,337,584 Baker Dec. 28, 1943 2,444,824

Hall July 6, 1948

